More than a year after buying a mega, yet-to-be-built project called Calico Solar and asking for regulatory approval to change the scope of the project, K Road Power filed a petition this week to modify the project again. This time, the company doesn't want to use stirling engines and plans to shrink the project's footprint in California's Mojave Desert to minimize its environmental impact.

The petition to amend the project is asking for approval to use only solar panels for the project instead of a mix of solar panels and stirling engines, which is a concentrating solar thermal technology that the project’s original owner was going to use exclusively. K Road also now intends to use 3,851 acres instead of 4,613 acres, and that means the generation capacity of the project also will fall from 663.5 MW to 618 MW.

The new request is the latest twist for a project that went through a long gestation period initially before finally gaining regulatory approval in 2010. It also reflected a shift in technology choice as solar panels have become a lot of cheaper in the past year thanks to an oversupply.

K Road’s proposed changes came after the developer went through a year of hearings to answer criticism about the project, which already was downsized from 850 MW to 663.5 MW when the California Energy Commission licensed it in December 2010. At the time, the commission said it cut the project’s footprint from 8,230 acres to 4,613 acres in order to preserve an important habitat for desert tortoise and bighorn sheep.

K Road bought Calico from Tessera Solar later in 2010 when Tessera was having trouble securing funds to continue the project and when Southern California Edison canceled its contract to buy power from the project. K Road asked the commission to change the scope of the project in March 2011; it was going to keep the footprint and generation size of the project but change the technology to be 100.5 MW of stirilng engines and 563 MW of solar panels on single-axis trackers.

The request to change the scope of the project triggered an additional review, which also opened up the project for public comments and critiques. The Sierra Club wanted to stop the project and filed a lawsuit just two days after K Road announced it had bought Calico. The California Supreme Court later tossed out the lawsuit without comment.

A stirling engine is a giant parabolic dish of mirrors that concentrate and direct sunlight to heat up hydrogen gas to run a 4-cylinder engine, which then drives a generator to produce electricity. Tessera’s sister company, Stirling Energy Systems, had spent years developing the technology for Calico.

Stirling Energy Systems declared bankruptcy in September, 2011. That prompted K Road to switch to using only solar panels. At the same time, it decided it wanted to modify the construction schedule.

A project as big as Calico naturally requires more time and planning to complete. K Road initially had hoped to start construction last year, however. And there is no word yet on who will buy the power from the project. The commission approved nine projects within months of one another in late 2010, and some have started construction more or less as planned.

But many haven’t started yet, including a massive 1,000-MW project called Blythe Solar that fell into limbo when its developer, Solar Trust of America, filed for bankruptcy in April this year. Earlier this week, a bankruptcy court judge approved the sale of Blythe to NextEra Energy, which bid $50 million for Blythe. The judge also approved the sale of another Solar Trust project, Palen, to BrightSource Energy, which offered $10 million.

BrightSource itself is currently building a 392-MW concentrating solar thermal power plant in the Mojave Desert and plans to complete it in 2013.